The Question:

What is the most popular pet for families to have in the United
States?

The Answer:

As of 2011, there were more dog owners (46.3 million households)
than cat owners (38.9 million households), but more pet cats (86.4
million) than pet dogs (78.2 million). That's because cat owners tend
to have more cats than dog owners have dogs. For the full set of
statistics, see Household Pet
Ownership.